149
FXUS65 KBYZ 111153
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
553 AM MDT SUN OCT 11 2026
KEY MESSAGES
- STRONG WEATHER SYSTEM IMPACTS THE REGION THROUGH MIDDAY MONDAY,
WITH HEAVY SNOW OVER THE WESTERN MOUNTAINS, ACCUMULATING WET
SNOW ALONG THE WESTERN FOOTHILLS, AND RAIN/WET SNOW FOR CENTRAL
LOWER ELEVATIONS. THE EAST WILL SEE OCCASIONAL RAIN.
- GOOD CHANCE OF A FREEZE ACROSS THE REGION MONDAY NIGHT.
- WEATHER PATTERN REMAINS UNSETTLED THROUGH MID WEEK, WITH SLOWLY
RISING TEMPS.
- GROWING CONFIDENCE FOR WARMER & DRIER WEATHER NEXT WEEKEND.
DISCUSSION
THROUGH NEXT SATURDAY...
SLOWLY-EVOLVING UPPER LOW OVER THE PACNW AND ANOMALOUSLY HIGH
ATMOSPHERIC MOISTURE IN THE SW FLOW ALOFT (AIDED BY REMNANTS OF
HURRICANE RACHEL) WILL CONTINUE TO BRING SIGNIFICANT PRECIPITATION
TO ESPECIALLY THE WEST HALF OF THE CWA TODAY THROUGH MIDDAY
MONDAY. ALL WINTER HIGHLIGHTS LOOK GOOD AND WILL MAKE NO CHANGES
AT THIS TIME. BOUNDARY LAYER COOLING IN THE WEST HAS HAPPENED
FASTER SINCE SATURDAY EVENING THAN PREVIOUSLY THOUGHT, BUT IT IS
UNCERTAIN IF THIS WILL TRANSLATE TO FORECAST DIFFERENCES MOVING
FORWARD.
CONFIDENCE IS HIGH THAT EVERYWHERE EAST OF MUSSELSHELL TO SHERIDAN
COUNTIES WILL SEE ONLY RAIN WITH THIS SYSTEM. THERE IS SIMPLY NOT
ENOUGH COOLER OR DRIER AIR TO ADVECT THROUGH EASTERN MT. DEWPTS IN
NORTHEAST MT ARE IN THE LOWER 40S. COOLEST CANADIAN AIR OVER THE
PAST 12HRS HAS SURGED THROUGH CENTRAL MT, GIVING FURTHER CREDENCE
TO WHAT WE ARE SEEING IN THE MODELS. ADDITIONALLY, GREATEST PRECIP
WITH THIS SYSTEM (1-1.5" AND LOCALLY UP TO 2") WILL BE FROM
BILLINGS WESTWARD.
GIVEN THE FAST TRANSITION TO SNOW ALONG THE WESTERN FOOTHILLS IT
IS POSSIBLE THAT SNOWFALL AMOUNTS IN THIS AREA END UP HIGHER THAN
CURRENTLY FORECAST, BUT THIS IS A TOUGH CALL PER THE WARM GROUND
AND MARGINAL AIR TEMPS. HAVE BUMPED UP SNOW ACCUMS A BIT AND WILL
CONTINUE TO MONITOR. LOCATIONS EAST OF THE IMMEDIATE FOOTHILLS
WILL SEE ONLY RAIN TODAY, BUT THEIR OPPORTUNITY FOR WET SNOW COMES
TONIGHT INTO MONDAY MORNING, COINCIDING WITH AN IMPRESSIVE
MOISTURE SURGE FROM THE SOUTH AND FURTHER COOLING OF THE BOUNDARY
LAYER. THE BULL MOUNTAINS ARE A SOLID CANDIDATE FOR SEVERAL INCHES
OF SNOW GIVEN THE ELEVATION, AND SIMILARLY THE HIGHER HILLS IN
GOLDEN VALLEY AND NORTHERN STILLWATER (THESE ZONES HAVE WINTER
WEATHER ADVISORIES STARTING SUNDAY EVENING). A TRICKIER FORECAST
EXISTS FROM BILLINGS TO JOLIET AND RED LODGE. LUTHER & RED LODGE
SHOULD SEE A LITTLE ACCUMULATION WHEN ALL IS SAID AND DONE. MODELS
SHOW A STRONG BACKING OF MID LEVEL WINDS TO EASTERLY LATE SUNDAY
AS RACHEL'S WAVE APPROACHES, WHICH BODES WELL FOR ENHANCED ASCENT
AND FURTHER DYNAMIC COOLING INTO EARLY MONDAY. THERE IS A FAIR
CHANCE (40%) FOR MEASURABLE SNOW OVER THE HILLS SURROUNDING
BILLINGS. THIS WILL BE SOMETHING TO WATCH CLOSELY TODAY.
THE WAVE EXITS MONDAY AFTERNOON AND PRECIP SHOULD BE TAPERED OFF
BY SUNSET. SURFACE HIGH OVER EASTERN MT SUPPORTS CLEARING AND
STRONG POTENTIAL FOR FREEZING TEMPS & AREAS OF FOG MONDAY NIGHT
INTO EARLY TUESDAY. FOR MUCH OF THE AREA THIS WILL BE THE FIRST
FROST/FREEZE OF THE FALL. TUESDAY IS LOOKING DRY BUT PROXIMITY TO
THE CUT OFF UPPER LOW OVER THE GREAT BASIN COULD BRING A FEW
SHOWERS OVER THE FAR SOUTH. TEMPS IN THE 30S & 40S TODAY & MONDAY
SHOULD RISE TO THE UPPER 40S TO MID 50S TUESDAY.
RAIN SHOWERS ARE POSSIBLE OVER SOUTHEAST MT WEDNESDAY AS THE
AFOREMENTIONED UPPER LOW KICKS THRU WY/SD/NE...THOUGH THERE IS
UNCERTAINTY IN ITS EXACT TRACK AND TIMING. INTO THURSDAY THERE IS
A CANADIAN CLIPPER THAT DROPS INTO THE NORTHERN PLAINS. TODAY'S
MODELS HAVE TRENDED FURTHER EAST AND DRIER W/ THIS WAVE, BUT EVEN
THEN THERE IS A LIKELIHOOD OF BREEZY NW WINDS AND MODERATELY
COOLER TEMPS. MSLP CLUSTERS SHOW HIGH UNCERTAINTY BUT IF A
REASONABLY STRONG/DRY SURFACE HIGH CLIPS EASTERN MT THURSDAY NIGHT
IT COULD PROVIDE A COLD NIGHT WITH A HARD FREEZE IN THE EAST.
LOOK FOR HIGH TEMPS IN THE 50S TO NEAR 60F WEDNESDAY & THURSDAY.
THERE IS GROWING CONFIDENCE FOR A BUILDING RIDGE TO BRING WARMING
AND DRYING TO END THE WEEK. FRIDAY SHOULD BEGIN THE WARMING,
THOUGH THAT DEPENDS ON THE STRENGTH OF THURSDAY'S CLIPPER. LOOK
FOR HIGHS BACK NEAR 70F SATURDAY. JKL
AVIATION
12Z TAF AND AVIATION DISCUSSION...WIDESPREAD RAIN (EAST) AND SNOW
(WEST) IS FORECAST TODAY THROUGH TONIGHT ACROSS THE FORECAST
AREA. EXPECT IFR TO LIFR CONDITIONS TO BE COMMON OVER THE WESTERN
HALF, WITH MVFR TO IFR OVER THE EAST. EASTERLY WINDS WILL ALSO
BRING FOG INTO THE FORECAST, ESPECIALLY LATE TONIGHT AS
PRECIPITATION BEGINS TO TAPER OFF. N-E WINDS WILL REMAIN GUSTY AT
15 TO 25KTS THROUGH THE DAY TODAY, TAPERING OFF THIS EVENING.
MOUNTAINS AND PASSES WILL BE OBSCURED TODAY THROUGH TONIGHT.
CHAMBERS
PRELIMINARY POINT TEMP/POPS
TDY MON TUE WED THU FRI SAT
-------------------------------------------------------
BIL 041 032/042 031/052 034/058 039/057 035/059 040/069
+/R +9/O 00/B 10/U 11/B 10/U 00/U
LVM 035 024/043 024/052 025/056 028/057 027/063 032/070
+/O +6/S 00/B 00/U 11/U 10/U 00/U
HDN 046 034/045 030/054 032/060 035/059 030/062 031/072
+/R +8/O 11/B 11/B 11/B 10/U 00/U
MLS 045 037/044 032/053 035/058 039/056 033/057 035/068
+/R 99/R 11/B 01/B 11/U 00/U 00/U
4BQ 053 042/048 032/054 038/058 041/057 034/058 037/070
8/R 76/R 23/W 23/W 31/B 11/U 00/U
BHK 050 032/046 030/054 031/059 034/058 028/056 030/068
8/R +8/R 11/E 11/B 21/N 10/U 00/U
SHR 049 034/046 029/053 032/057 035/057 028/061 032/071
8/R 83/R 34/W 44/W 31/N 10/U 00/U
BYZ WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO
NOON MDT MONDAY FOR ZONES 29-34-42.
WINTER WEATHER ADVISORY IN EFFECT UNTIL NOON MDT MONDAY FOR
ZONES 40-65-66-141-228.
WINTER STORM WARNING IN EFFECT UNTIL NOON MDT MONDAY FOR
ZONES 63-67-68-172.
WY...NONE.
WEATHER.GOV/BILLINGS
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